Becker,
I had the same issue several times and here's what I did and it solved the problem. Before you start disassembling the motor or the gears try this:
Crawl underneath (behind the steps) and gently tap on the curved arm that extends from the step motor while someone opens and closes the door. Be sure to be behind in case the steps deploy. Once the steps open, thoroughly lubricate every joint and pivot points with Kwik lube spray grease. This product will spray like a liquid and turn to a grease lubricant.
Hope this helps.
Safe travels
Paddy Drumm